Japanese Patent Application Laid-Open Publication No. 2002-305013 discloses a vehicular fuel cell system which, during start-up of a vehicle at a low temperature condition such as a below-freezing temperature, permits a fuel cell stack to generate electric power at a predetermined power to achieve warm-up of a fuel cell prior to commencement to travel the vehicle, and which discriminates to find whether the warm-up of the fuel cell stack has been completed, referring to an air electrode (cathode) exhaust gas temperature, a temperature difference between an air electrode intake air and an air electrode exhaust, and a temperature factor such as a temperature of coolant, thereby providing the vehicle with a run permission (see FIG. 3 and its related description).